Inflatable safety restraint devices, or airbags, are mandated in most new highway vehicles. Airbags are typically included at least in the steering wheel and in the dashboard on the passenger side of a highway vehicle. In addition, such airbags are occasionally installed to inflate beside a vehicle occupant and provide side impact protection, to inflate in front of the legs and protect the knees from forward impact, or to inflate at other strategic locations within the occupant enclosure of a highway vehicle.
In the event of an accident, a collision sensor within the vehicle detects an impact situation and stimulates an inflator to produce pressurized gas. That pressurized gas is directed into an associated airbag cushion, filling the cushion of the airbag, which then prevents a vehicle rider from impacting directly the interior surfaces of the occupant enclosure. The generation of compressed gas occurs in a combustion chamber in the inflator and is commenced typically through the electrical detonation of a small pyrotechnic initiator within the combustion chamber. Inflatable airbag cushions with associated inflators and initiators are usually manufactured together as passenger vehicle safety airbag modules, which are installed unit-wise at appropriate locations in vehicles.
A passenger-side, frontal-impact passenger vehicle safety airbag module is commonly installed behind the instrument panel of a vehicle at an airbag cushion deployment window formed therethrough. The initiator in the inflator of the module is placed in electrical communication with the collision sensor of the vehicle.
Pressurized inflation gas leaving the combustion chamber of an initiator often entrains undesirable particulate debris produced by the pyrotechnic processes in the combustion chamber that gave rise to the inflation gas. This debris can potentially cause damage to the airbag cushion into which the inflation gas is directed. Accordingly, passenger vehicle safety airbag modules routinely make provisions for the removal of such debris from pressurized inflation gas before it leaves the inflator and enters the cushion of the airbag in the module. For example, many airbag modules make use of a filter pack through which the expanding gases travel before filling the airbag cushion. Such filter packs can prevent particulate from leaving the inflator, and can remove heat from the combustion gases prior to entering the airbag cushion. However, the filter pack typically represents a relatively heavy and expensive component of the inflator. Accordingly, it is desirable to provide one or more alternatives that may be employed in place of a conventional filter pack.